<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<html>
  <head>
    <meta name="viewport" content="user-scalable=no" />
    <meta name="Generator" content="EditPlus" />

    <meta name="Author" content="" />

    <meta name="Keywords" content="" />

    <meta name="Description" content="" />

    <style>
      html,
      body {
        height: 100%;

        padding: 0;

        margin: 0;

        background: #000;
      }

      canvas {
        position: absolute;

        width: 100%;

        height: 100%;
      }

      .child {
        position: fixed;

        top: 50%;

        left: 50%;

        transform: translate(-50%, -50%);
      }

      h4 {
        font-size: 25px;
        color: #ea80b0;
      }

      input {
        position: fixed;
        top: 0;
        left: 0;
        font-size: 25px;
        color: #ea80b0;
        background-color: transparent;
        outline: 0;
        border: 0;
        z-index: 1000;
      }

      button {
        display: none;
        position: fixed;
        top: 50px;
        left: 0;
        z-index: 1000;
      }
    </style>
  </head>

  <body>
    <input type="text" /><button>确认</button>
    <div class="child"><h4></h4></div>

    <canvas id="pinkboard"></canvas>

    <script>
      /*

* Settings

*/

      var settings = {
        particles: {
          length: 500, // maximum amount of particles

          duration: 2, // particle duration in sec

          velocity: 100, // particle velocity in pixels/sec

          effect: -0.75, // play with this for a nice effect

          size: 30, // particle size in pixels
        },
      };

      /*

* RequestAnimationFrame polyfill by Erik Möller

*/

      (function () {
        var b = 0;
        var c = ["ms", "moz", "webkit", "o"];
        for (var a = 0; a < c.length && !window.requestAnimationFrame; ++a) {
          window.requestAnimationFrame = window[c[a] + "RequestAnimationFrame"];
          window.cancelAnimationFrame =
            window[c[a] + "CancelAnimationFrame"] ||
            window[c[a] + "CancelRequestAnimationFrame"];
        }
        if (!window.requestAnimationFrame) {
          window.requestAnimationFrame = function (h, e) {
            var d = new Date().getTime();
            var f = Math.max(0, 16 - (d - b));
            var g = window.setTimeout(function () {
              h(d + f);
            }, f);
            b = d + f;
            return g;
          };
        }
        if (!window.cancelAnimationFrame) {
          window.cancelAnimationFrame = function (d) {
            clearTimeout(d);
          };
        }
      })();

      /*

* Point class

*/

      var Point = (function () {
        function Point(x, y) {
          this.x = typeof x !== "undefined" ? x : 0;

          this.y = typeof y !== "undefined" ? y : 0;
        }

        Point.prototype.clone = function () {
          return new Point(this.x, this.y);
        };

        Point.prototype.length = function (length) {
          if (typeof length == "undefined")
            return Math.sqrt(this.x * this.x + this.y * this.y);

          this.normalize();

          this.x *= length;

          this.y *= length;

          return this;
        };

        Point.prototype.normalize = function () {
          var length = this.length();

          this.x /= length;

          this.y /= length;

          return this;
        };

        return Point;
      })();

      /*

* Particle class

*/

      var Particle = (function () {
        function Particle() {
          this.position = new Point();

          this.velocity = new Point();

          this.acceleration = new Point();

          this.age = 0;
        }

        Particle.prototype.initialize = function (x, y, dx, dy) {
          this.position.x = x;

          this.position.y = y;

          this.velocity.x = dx;

          this.velocity.y = dy;

          this.acceleration.x = dx * settings.particles.effect;

          this.acceleration.y = dy * settings.particles.effect;

          this.age = 0;
        };

        Particle.prototype.update = function (deltaTime) {
          this.position.x += this.velocity.x * deltaTime;

          this.position.y += this.velocity.y * deltaTime;

          this.velocity.x += this.acceleration.x * deltaTime;

          this.velocity.y += this.acceleration.y * deltaTime;

          this.age += deltaTime;
        };

        Particle.prototype.draw = function (context, image) {
          function ease(t) {
            return --t * t * t + 1;
          }

          var size = image.width * ease(this.age / settings.particles.duration);

          context.globalAlpha = 1 - this.age / settings.particles.duration;

          context.drawImage(
            image,
            this.position.x - size / 2,
            this.position.y - size / 2,
            size,
            size
          );
        };

        return Particle;
      })();

      /*

* ParticlePool class

*/

      var ParticlePool = (function () {
        var particles,
          firstActive = 0,
          firstFree = 0,
          duration = settings.particles.duration;

        function ParticlePool(length) {
          // create and populate particle pool

          particles = new Array(length);

          for (var i = 0; i < particles.length; i++)
            particles[i] = new Particle();
        }

        ParticlePool.prototype.add = function (x, y, dx, dy) {
          particles[firstFree].initialize(x, y, dx, dy);

          // handle circular queue

          firstFree++;

          if (firstFree == particles.length) firstFree = 0;

          if (firstActive == firstFree) firstActive++;

          if (firstActive == particles.length) firstActive = 0;
        };

        ParticlePool.prototype.update = function (deltaTime) {
          var i;

          // update active particles

          if (firstActive < firstFree) {
            for (i = firstActive; i < firstFree; i++)
              particles[i].update(deltaTime);
          }

          if (firstFree < firstActive) {
            for (i = firstActive; i < particles.length; i++)
              particles[i].update(deltaTime);

            for (i = 0; i < firstFree; i++) particles[i].update(deltaTime);
          }

          // remove inactive particles

          while (
            particles[firstActive].age >= duration &&
            firstActive != firstFree
          ) {
            firstActive++;

            if (firstActive == particles.length) firstActive = 0;
          }
        };

        ParticlePool.prototype.draw = function (context, image) {
          // draw active particles

          if (firstActive < firstFree) {
            for (i = firstActive; i < firstFree; i++)
              particles[i].draw(context, image);
          }

          if (firstFree < firstActive) {
            for (i = firstActive; i < particles.length; i++)
              particles[i].draw(context, image);

            for (i = 0; i < firstFree; i++) particles[i].draw(context, image);
          }
        };

        return ParticlePool;
      })();

      /*

* Putting it all together

*/

      (function (canvas) {
        var context = canvas.getContext("2d"),
          particles = new ParticlePool(settings.particles.length),
          particleRate =
            settings.particles.length / settings.particles.duration, // particles/sec
          time;

        // get point on heart with -PI <= t <= PI

        function pointOnHeart(t) {
          return new Point(
            160 * Math.pow(Math.sin(t), 3),

            130 * Math.cos(t) -
              50 * Math.cos(2 * t) -
              20 * Math.cos(3 * t) -
              10 * Math.cos(4 * t) +
              25
          );
        }

        // creating the particle image using a dummy canvas

        var image = (function () {
          var canvas = document.createElement("canvas"),
            context = canvas.getContext("2d");

          canvas.width = settings.particles.size;

          canvas.height = settings.particles.size;

          // helper function to create the path

          function to(t) {
            var point = pointOnHeart(t);

            point.x =
              settings.particles.size / 2 +
              (point.x * settings.particles.size) / 350;

            point.y =
              settings.particles.size / 2 -
              (point.y * settings.particles.size) / 350;

            return point;
          }

          // create the path

          context.beginPath();

          var t = -Math.PI;

          var point = to(t);

          context.moveTo(point.x, point.y);

          while (t < Math.PI) {
            t += 0.01; // baby steps!

            point = to(t);

            context.lineTo(point.x, point.y);
          }

          context.closePath();

          // create the fill

          context.fillStyle = "#ea80b0";

          context.fill();

          // create the image

          var image = new Image();

          image.src = canvas.toDataURL();

          return image;
        })();

        // render that thing!

        function render() {
          // next animation frame

          requestAnimationFrame(render);

          // update time

          var newTime = new Date().getTime() / 1000,
            deltaTime = newTime - (time || newTime);

          time = newTime;

          // clear canvas

          context.clearRect(0, 0, canvas.width, canvas.height);

          // create new particles

          var amount = particleRate * deltaTime;

          for (var i = 0; i < amount; i++) {
            var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());

            var dir = pos.clone().length(settings.particles.velocity);

            particles.add(
              canvas.width / 2 + pos.x,
              canvas.height / 2 - pos.y,
              dir.x,
              -dir.y
            );
          }

          // update and draw particles

          particles.update(deltaTime);

          particles.draw(context, image);
        }

        // handle (re-)sizing of the canvas

        function onResize() {
          canvas.width = canvas.clientWidth;

          canvas.height = canvas.clientHeight;
        }

        window.onresize = onResize;

        // delay rendering bootstrap

        setTimeout(function () {
          onResize();

          render();
        }, 10);
      })(document.getElementById("pinkboard"));
    </script>

    <script>
      const input = document.querySelector("input");
      const h4 = document.querySelector("h4");
      const btn = document.querySelector("button");
      let text = "";
      input.addEventListener("input", (e) => {
        text = e.target.value;
        btn.style.display = "block";
      });

      btn.onclick = () => {
        btn.style.display = "none";
        h4.innerHTML = text;
        input.value = "";
      };
    </script>
  </body>
</html>
